Frank Berger has provided a detailed, stepwise account of the sexual revolution during the past half century or so.
In course of explaining the spiritual causes of what is going on in Western Societies, he references Rudolf Steiner's 1918 prophecy (contained in Work of the Angels in Man's Astral Body) that I have discussed often on this blog.
In terms of prophecy, I would add the short dystopian novella Night Operation by Owen Barfield (1975) - a section of which can be seen here.
In short, Barfield was aware that human sexuality was likely to become perverted, inverted and evil - as a matter of official approval and public policy. Significantly, Barfield was a co-translator of the Steiner 1918 lecture.